Polyphenylene ether resin, or a mixture of a polyphenylene ether resin and a polystyrene resin, is widely used in various applications such as automobile parts, electrical parts, and electronic parts due to its excellent mechanical and electrical properties at a high temperature. However, polyphenylene ether resin has poor chemical resistance and workability.
Polyamide resin has good chemical resistance and workability, but poor heat resistance and dimensional stability, and a high moisture absorption ratio. Therefore, there are limited applications for the same as an engineering plastic resin.
A combination of the two resins can provide improved chemical resistance, workability, and heat resistance and can provide engineering plastic resins having an excellent balance of properties.
In order to provide such a resin with conductivity, a conductive additive such as carbon black, carbon nanotube, a carbon fiber, a metal powder, a metal-coated inorganic powder, or a metal fiber may be used. However, when the carbon black is added in a significant amount (more than or equal to 3 wt % with respect to the total amount of a resin composition), sufficient electrical conductivity may not be ensured. In addition, while when a large amount of the conductive additive is added, basic mechanical properties of an electrically conductive thermoplastic resin such as impact resistance and the like may be significantly decreased.
Carbon fiber can be an excellent additive for providing electrical conductivity and enhancing strength but it can result in poor surface quality of a composite and can also deteriorate impact strength and elongation.
Carbon nanotubes are conductive additives having excellent electrical conductivity and a high aspect ratio. Carbon nanotubes may provide a resin with electrical conductivity even when used in a small amount, but also can deteriorate impact strength. In addition, carbon nanotubes may cause problems of adsorbing additives, particularly, a reactive monomer on the surface thereof which can interfere with the function of the additive.